help interpreting electric arc variations using Casper's C3I to test coilpaks & ignition modules

[Anthony P]

using the C3I ignition simulator on GM + aftermarket coilpaks attached to GM ignition modules -

When at full RPM simulation (8000), some of the electrical arcs for the individual coils form a multiple-stranded arc rather than a single arc between the washers. Please refer to attached pics. I'm testing multiple coilpaks (used and new - ACDelco and SMP DR36 versions).

The multiple-strand arc occurs at top-end simulation, when the audible frequency changes to the highest pitch. Also, with these multiple-strand arcs, there is audible "static" at a lower frequency that can be heard.

The multi-strand arcs can occur on both new and old coilpaks, regardless of brand. FWIW, the applications are for stock or near stock GN's producing maybe a max of 16-17 psig boost via a turbotweak street chip.


What is the electrical terminology to explain what is happening here?

Is the formation of a multiple-stranded arc an indication that respective coil is experiencing a breakdown?

And that while that coil still fires, the multiple-stranded arc is illustrative of a weaker electrical field and cooler spark that could become problematic under boost?

 

[grass doctor]

I can't get the video on here , did not see this multiple arc on ones I tested , but sent you a video

 

[Anthony P]

Thanks Matt. watched video. I'm expecting a single arc like on the 3-6 coil in the second pic above. the multi-strand arcs form at the last 20 % rotation of the dial.

I have some early 1990s GM coilpaks that test perfectly showing a single arc throughout the simulation.

It's the new and brand new coilpaks doing this multi-strand thing. All 3 of the Standard Motor Products DR36 coilpaks just purchased and one of the newer Delco D552 do this. The SMP coilpaks are date coded 284th day of 2018, so they are fresh inventory from their Virginia warehouse (V18284). SMP coilpaks are made in the same factory in Poland that makes the Delphi coilpaks, and probably many of the other brands as well. the newer Delco unit is made in china.

Hopefully someone here can explain what's happening. If not, I guess I can contact the electrical engineering dept at my alma mater. RC is a EE as well...just may call Richard tomorrow.

 

[Pronto]

Not to be a wise ass but the application of a near stock engine at 17 psi is never going to be operated at 8k rpm. 80% is still 6400 rpm. Now i think I've read the new modules are not built to the same specs. Maybe that has something to do with it? That doesn't explain the older coils packs working though.

 

[grass doctor]

have you tested one of the high output coil packs, curious on those , all the ones I tested are older gm ones so glad I have those as they appear not do the Multiarc thing

 

[turbo nasty]

@GNVenom

 

[Anthony P]

Not to be a wise ass but the application of a near stock engine at 17 psi is never going to be operated at 8k rpm. 80% is still 6400 rpm. Now i think I've read the new modules are not built to the same specs. Maybe that has something to do with it? That doesn't explain the older coils packs working though.

hey Pronto, from what Casper's John Spina had previously explained to me was that the 8000 RPM max simulation is intended to indicate what's happening under boost for our low revving engines (5500 to 6500 RPM).

have you tested one of the high output coil packs, curious on those , all the ones I tested are older gm ones so glad I have those as they appear not do the Multiarc thing

hey Matt, no I have not done any of those "high output" coilpaks. for me, i did not see the need as I'm at basically a stock engine.

 

[Anthony P]

@GNVenom

hey turbo nasty, I submitted this directly to John & Justin via the Casper's website on July 25th. No reply so I decided to add it here as well. thought going directly thru their website would get this question into their hands more quickly rather than sending John a PM here. don't know how often he signs-on to read messages. the only way I find out about new messages waiting for me is by signing in. the email notification has not worked for me for many years now.

 

[Anthony P]

MULTI-STRAND ARC SOLVED!

Spoke with John at Casper's today. the short answer to why this was happening is: LOW VOLTAGE.

To recap:

I purchased some new Standard Motor Products DR-36 coilpaks. Before putting them on the spare parts shelf and certainly before using on an engine, I will always test a part to verify operation. And I decided to test some other used Delco coilpaks and ignition modules while I'm at it. At top end simulation with the Casper's C3I tool, the electrical arcs became multi-stranded. see pics in first post. That result had me thinking these parts were defective.

My benchtop 12VDC powersource is an Optima battery. battery was fully charged, showing 12.6VDC (at rest) when I began this testing. At the conclusion of testing, resting voltage dropped to 12.2VDC, so I hooked up the battery tender to recharge my power source.

Here are the takeaways from my conversation with John:

--voltage lower than the car's system when operating can cause all sorts of weird stuff happening. so much so that good parts can appear to malfunction.

--AGM batteries like the Optima will have a lower voltage than a wet (lead-acid) battery when charging. suggested redoing my tests with a fully charged wet battery instead of using an AGM battery as a power source.

--always attach the C3I tester's leads directly to the battery. some cars have the battery relocated to the trunk. in this case, using power taps in the engine bay to power the tester is a bad choice. There can be increased inductance from the length of those battery cables traversing the length of the car which will negatively affect the testing.

to solve the lower voltage problem at the workbench, I hooked up a 10A charger to the Optima battery. Even though the battery was taking a charge of a few amps, I began testing with voltage reading about 14.1 VDC. I also hooked up a meter to record the voltage during testing.

As you can see in the pic below, all checks out OK when testing at 14VDC. the multi-strand arcs are gone. the expected single arcs are evident. the other coilpaks and ignition modules that exibited malfunctions during testing at the lower 12.1 to 12.3VDC range all function normally at the higher voltage of 14.

something to keep in mind that sub-optimal charging system voltage can make a whole lot of gremlins appear. John did say that is why they produced the volt-booster product.